A poker tournament is a tournament in which the winners are decided by playing poker, usually a particular style of poker.

Contrast this to a ring game, where the game is ongoing with no formal structure to determine a single winner in a certain length of time.

Buy-ins and prizes

To enter a typical tournament, a player pays a fixed buy-in and at the start of play is given a certain quantity of tournament poker chips. Commercial venues may also charge a separate fee, or withhold a small portion of the buy-in, as the cost of running the event. Tournament chips have only notional value; they have no cash value, and only the tournament chips, not cash, may be used during play. Typically, the amount of each entrant's starting tournament chips is an integer multiple of the buy-in. Some tournaments offer the option of a re-buy or buy-back; this gives players the option of purchasing more chips. In some cases, re-buys are conditional (for example, offered only to players low on or out of chips) but in others they are available to all players (called add-ons). When a player has no chips remaining (and has exhausted or declined all re-buy options, if any are available) he or she is eliminated from the tournament.

In most tournaments, the number of players at each table is kept even by moving players, either by switching one player or (as the field shrinks) taking an entire table out of play and distributing its players amongst the remaining tables. A few tournaments, called shoot-outs, do not do this; instead, the last player (sometimes the last two or more players) at a table moves on to a second or third round, akin to a single-elimination tournament found in other games.

The prizes for winning are usually derived from the buy-ins, though outside funds may be entered as well. For example, some invitational tournaments do not have buy-ins and fund their prize pools with sponsorship revenue and/or gate receipts from spectators. (These tournaments are referred to as freerolls.) Play continues, in most tournaments, until all but one player is eliminated, though in some tournament situations, especially informal ones, players have the option of ending by consensus.

Players are ranked in reverse chronological order — the last person in the game earns 1st place, the second-to-last earns 2nd, and so on. This ranking of players by elimination is unique amongst games, and also precludes the possibility of a tie for first place, since one player alone must have all the chips to end the tournament. (Ties are possible for all other places, though they are rare since the sole tiebreaker is the number of chips one has at the start of the hand in which one is eliminated, and hence two people would need to start a hand with the exact same number of chips and both be eliminated on that same hand in order to tie each other.)

Sometimes tournaments end by mutual consensus of the remaining players. For example, in a ten-person, $5 game, there may be two players remaining with $29 and $21, respectively, worth of chips. Rather than risk losing their winning, as one of them would if the game were continued, these two players may be allowed to split the prize proportional to their in-game currency (or however they agree).